On 2020/9/10 16:58, Christian König wrote:

Am 10.09.20 um 04:38 schrieb Jing Xiangfeng:

...

The macro 'DECLARE_NEXT_HOLE_ADDR' may hit a potential null-pointer dereference. So use 'entry' after checking it.

I don't see a potential null-pointer dereference here.

Where should that be?

In current code，the "entry" pointer is checked after entry->rb_hole_addr. Thanks

Christian.

...

Fixes: 5fad79fd66ff ("drm/mm: cleanup and improve next_hole_*_addr()") Signed-off-by: Jing Xiangfeng jingxiangfeng@huawei.com

---

drivers/gpu/drm/drm_mm.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index a4a04d246135..6fcf70f71962 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -392,11 +392,14 @@ first_hole(struct drm_mm *mm, #define DECLARE_NEXT_HOLE_ADDR(name, first, last) \ static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size) \ { \

• struct rb_node *parent, *node = &entry->rb_hole_addr; \

• struct rb_node *parent, *node; \ \

• if (!entry || RB_EMPTY_NODE(node)) \

• if (!entry) \ return NULL; \ \
• node = &entry->rb_hole_addr; \
• if (RB_EMPTY_NODE(node)) \

•    return NULL;                        \
  if (usable_hole_addr(node->first, size)) {            \
      node = node->first;                    \
      while (usable_hole_addr(node->last, size))        \
  

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